This competing continuation application proposes to use much more refined methods to test hypotheses generated from our initial grant (a FIRST award), which examined the mechanisms of visual processing abnormalities in schizophrenia patients and their siblings. Based on our initial series of studies, we hypothesize that schizophrenia patients have dual deficits involving both early (sensory/perceptual) and later (attentional disengage) processes. We hypothesize that the problem in the early component stems from overactive transient visual channel activity. In contrast, we hypothesize that siblings of the patients show deficits on the early, but not later component of visual masking. The current proposal also includes an attentional manipulation of readiness to determine whether performance can be modified under these conditions. We will also make critical advances in our studies of early visual processing deficits as vulnerability factors for schizophrenia. Vulnerability to schizophrenia can be studied by assessing First-degree relatives of patients and by assessing patients when they are in remission. We will do both. We will expand our work with visual processing in the siblings of chronic schizophrenia patients to test the hypothesis that siblings show evidence of overactive transient channels in the early masking component, but a normal degree of attentional disengagement in the later masking component. We hypothesize that remitted schizophrenia patients will also show deficits in the early masking component. Remitted bipolar patients are included to address the diagnostic specificity of this vulnerability factor. In an exploratory component, the current proposal will provide the first opportunity to assess the siblings of schizophrenia patients on the pre-pulse inhibition of startle blink, which has certain procedural and conceptual similarities to visual masking. The basic approach for these studies is "experimental reductivism" in which the goal is to parse a complex cognitive deficit relevant to schizophrenia into its smallest meaningful units. Identification of these basic cognitive components will help us to refine our conceptualization of the specific aspects of cognition that are associated with vulnerability to schizophrenia.